The proposed project is aimed to develop a novel ultrasonic approach for manipulating small biological particles including cells, termed acoustic tweezer. In the proposal, the force calibration method of acoustic tweezers is presented and two methods, using such as viscous drag force and power spectrum analysis, are described, and their results will be compared to check the accuracy of both approaches. To find more diverse applications, it is crucial to define various trapping modes, typically, of Rayleigh regime and solid elastic particles. Based on our experimental findings of both modes, its theoretical analysis will be carried out by considering Rayleigh scatterings as well as shear wave generation in elastic materials. In order to manipulate cellular level particles in acoustic traps, ultra-high frequency focused transducers (>100 MHz) will be designed and fabricated. Tight focusing will be achieved by either sputtering piezoelements, e.g., ZnO on a curved substrate, or using materials of thin/thick PZT films. Biomedical in-vitro applications of acoustic tweezers will then be sought, combined with the aforementioned results, and that includes in-vitro cellular interaction study of red blood cells, white blood cell-endothelial cells, and drug-carrying lipospheres-cancer cells. Successful completion of the project would provide a new alternative for manipulating small biological particles that produces stronger forces than those from optical tweezers, and is yet safer to control living cells without causing any physical damage. PUBLIC HEALTH RELEVANCE: The objective of the proposed project is to develop a novel ultrasonic approach for manipulating small biological particles including cells, termed acoustic tweezer. It is so named because the physical principles involved are identical to optical tweezers. Preliminary results from theoretical analyses and experiments supported by a R21 grant have shown that lateral trapping of lipid particles is possible. In the present R01 application, four specific aims are proposed to further develop the approach. They will be directed at a thorough fundamental investigation of the acoustic tweezer phenomenon and at exploring its biomedical applications in collaboration with well-known investigators, who have either previous experience with optical tweezers or a need to utilize this technology. The specific aims are (1) force calibration of acoustic tweezers, (2) definition of other acoustic trapping modes, (3) development of ultra-high frequency acoustic tweezers (>100 MHz), and (4) exploration of biomedical applications for in-vitro cellular study. The 1st and 2nd specific aims must be carried out if the acoustic tweezer is to be utilized for quantitative measurements. The 3rd and 4th specific aim would allow the acoustic tweezer to be used for studying biological particles as small as red blood cells and for potential applications in quantitative in-vitro measurements of red cell-red cell interaction and white cell-endothelial cell interaction in collaboration with established investigators in these areas. Successful completion of the project would mean the availability of a new tool for manipulating small biological particles that yields trapping forces higher than those from optical tweezers. It would complement optical tweezers when there may be the danger of photodamage since the energy level of acoustic tweezers needed to produce similar magnitude of forces is smaller than optical tweezers.